Free Response: ECOLOGY
Describe the process of ecological succession from a pioneer community
to a climax community. Include in your answer a discussion of species
diversity and interactions, accumulation of biomass, and energy flow.
STANDARDS:
DESCRIPTION
__ Definition of Succession
__ Differentiation (Primary/Secondary)
Examples:
__ Pioneer
__ Climax
__ Seral
SPECIES DIVERSITY
__ Explanation of increase
__ Types of Competition (or Niche)
__ Examples
__ Change in Population Density
BIOMASS
__ Levels of Organization (Autotrophs & Heterotrophs)
__ Examples of Producers (etc.)
__ Pyramid or Explanation
ENERGY
__ Source (Sun)
__ Photosynthesis
__ One Way Transfer
Free Response: ECOLOGY
Describe the biogeochemical cycles of carbon. Trace these
elements from the point of their release from a decaying animal to
incorporation into a living animal.
their
STANDARDS:
For the CARBON CYCLE, it was possible to earn points for each of the following
statements
or ideas:
__ Explanation of the role of green plants as producers
__ Mention of herbivores in a way that indicated an understanding of their
role
__ An indication that carnivores obtained C from herbivores
__ Discussion of the role of decomposers in returning C to the atmosphere as
CO2
__ Mention of CO2 production via respiration of green plants, herbivores or
carnivores
__ Discussion of the C in oil, natural gas, and coal as originating from the
remains of organisms
__ Mention of CO2 release to the atmosphere through the burning of fuel.
__ Discussion of carbon found in ocean and terrestrial reservoirs
__
An indication that human activity had a significant impact on the carbon
cycle.
__ The significance of disruptions to the carbon cycle.
Free Response: ECOLOGY
Describe the biogeochemical cycles of nitrogen. Trace these
elements from the point of their release from a decaying animal to
incorporation into a living animal.
their
STANDARDS:
__ An indication that organic molecules were broken down after death
__ Discussion of nitrifying bacteria
__ Discussion of denitrification
__ Discussion of nitrification
__ Mentioning the role of microbes, or lightning in affecting atmosheric
nitrogen.
__ Understanding that atmospheric nitrogen has a triple bond and requires a
lot of energy to break apart.
__ Indication that nitrogen can be taken up by organisms
__ Indication that plants use absorbed nitrogen to make proteins
__ An understanding of the conversion by animals of plant proteins into animal
proteins
__ Indication that on death or in excretion organic nitrogen is released into
the environment.
__ Indication of a significant impact of human activity on the nitrogen cycle.
__ The significance of disruptions to the nirtogen cycle.
Free Response: ECOLOGY
Using an example for each, discuss the following ecological concepts.
a) Succession
b) Energy flow between trophic levels
c) Limiting factors
d) Carrying capacity
STANDARDS:
a) SUCCESSION:
__ Definition:
demonstrate process of change in communities through time
__
modification of environment/transition of species composition
__ Examples:
generalized - lake -> marsh -> meadow -> forest
Specific - lichen -> moss -> herbs -> shrubs -> forest
__ Primary
- no life/soil -> pioneer organisms/soil development
__ Secondary - disturbance -> climax/stable community
b) ENERGY FLOW BETWEEN TROPHIC LEVELS:
__ Examples:
grass -> locust -> mouse -> snake
grass -> herbivore -> carnivore -> detritivore
producer -> 1' consumer -> 2' consumer -> 3' consumer
food chain/web - elaboration of trophic levels
__ Producers (autotrophs) start energy flow
__ Consumers (heterotrophs) acquire energy from primary producers
__ Efficiency - 10% rule/90% energy loss or pyramid of energy
c) LIMITING FACTORS:
__ Definition: any factor operating to restrict population growth
Examples:
__ biotic - population density, competition, predation
__ abiotic - moisture, temperature, weather/climate, wind, sunlight, soil,
topography, geographic location, nutrients
__ density-dependent - change birth/death rate as density changes
__ density-independent - change birth/death rate regardless of density
d) CARRYING CAPACITY:
__ Definition: number of individuals of a population (species) sustainable by
an environment(as long as the environment remains the same)
__ Examples: predator/prey; rabbits in Australia; deer on Kaibab; human
population;
__ Limiting factor(s) determine carrying capacity (competition, waste,
predation)
__ Population grows -> rate slows -> stabilize (N decreases)
or
__ Population falls -> growth resumes -> stabilizes (N decreases)